1. Field of the Invention
The present invention pertains to an ambulatory liquefied gas system, and, in particular, to a system and method for filling a portable liquefied gas storage/delivery unit from a liquefied gas storage system.
2. Description of the Related Art
The delivery of supplemental oxygen to a patient is typically prescribed for individuals suffering from pulmonary/respiratory problems. The prescription and delivery of supplemental oxygen is undertaken to ensure that sufficient oxygen levels are received by the patient. Situations where supplemental oxygen may be prescribed include individuals afflicted with a chronic obstructive pulmonary disease, such as asthma, as well as individuals suffering from diseased or damaged lungs.
It is known to deliver supplemental oxygen using a liquid oxygen (“LOX”) system. A conventional LOX system includes a large stationary LOX storage canister that is located at and remains in the user's home. The stationary LOX canister is replenished periodically from a mobile LOX storage vessel, which is typically a truck carrying a large quantity of LOX. A conventional LOX system also includes a small, portable storage/delivery apparatus weighing from five to thirteen pounds that can be filled from the stationary unit for trips outside the home.
One such LOX system is disclosed in U.S. Pat. No. 6,742,517 (“the '517 patent”) entitled, High Efficiency Liquid Oxygen Storage and Delivery System. As disclosed in this patent, a typical LOX system includes a stationary LOX storage canister located in an individual's home and a portable LOX delivery unit that the patient uses outside the home. The name of the portable delivery unit in the commercial implementation of this LOX system and described in the '517 patent is the HELiOS®. As identified at the HELiOS website, www.heliosoxygen.com, the HELiOS H300 portable LOX delivery unit has a limited capacity for storing liquid oxygen.
The HELiOS system is refilled by firmly forcing the HELiOS H300 portable LOX delivery unit onto the LOX storage canister by pressing down on the HELiOS H300 portable LOX delivery unit to cause it to engage with the LOX storage canister. While forcing the HELiOS H300 portable LOX delivery unit onto the LOX storage canister the user must manually move a vent valve level on the exterior of the portable deliver unit to an open position. This requires simultaneously applying a downward force on the HELiOS H300 portable LOX delivery unit and moving the valve level. Naturally, this requires using both hands or using more than one person to fill the portable delivery unit.
During filling, the user must maintain a watch on the HELiOS H300 portable LOX delivery unit until sputtering in the filling noise associated with the filling of the unit. In addition, the user must watch for the release of white vapor from the HELiOS H300 portable LOX delivery unit in order to ensure that the unit has been completely filled. After which, the user is instructed to release the portable LOX delivery unit from the storage canister.
In another system, such as the Stroller/Spirit sold by Caire, Inc., the portable LOX delivery unit can be attached to the LOX storage canister. This requires engaging a connector on the portable LOX delivery unit with a connector of the LOX storage canister. There is no interconnection between the portable LOX delivery unit and the LOX storage canister other than the connector-to-connector coupling. The coupling process also requires manually rotating or turning the portable LOX delivery unit relative to the LOX storage canister to engage the coupling on the portable LOX delivery unit with the coupling on the LOX storage canister. Once the couplings are engaged, the user must maintain a vigil over the portable LOX delivery unit to determine when the unit has been filled.